An apparatus for debugging internal signals of integrated circuits is presented. In one embodiment, the apparatus comprises a number of vector registers associated with states of a state machine. A group of registers, associated with a state of the state machine, comprises a mask register an arm register. A comparator compares debug data with contents of the mask register and the arm register to determine a comparison result to be stored in one or more bit positions of the vector register. The apparatus further comprises a triggering logic unit to determine whether or not to trigger a fire event based on the vector registers.